1. Field of the Invention
The present invention relates to an optical disc apparatus having functions for judging sizes of optical discs, and for judging stop of rotation of the optical disc.
2. Description of the Related Art
In the conventional optical disc apparatus, a tray is opened after stopping rotation of the optical disc, disposing the optical disc on the tray by lowering a turn table, and sliding the tray in front of the optical disc apparatus. The turn table is controlled to move downward after sensing the stop of rotation of the optical disc so as not to scratch a surface of the optical disc.
In the conventional optical disc apparatus, a frequency generator system is used for sensing the rotation speed of the optical disc, so that the stop of rotation of the optical disc can be sensed by the frequency generator. The frequency generator can be used for judging the size of the optical disc mounted on the turn table corresponding to the variation of the rotation speed of the optical disc. Thus, a spindle motor for rotating the optical disc can be controlled corresponding to the size of the optical disc.
The frequency generator is configured by a pattern of reflexive portions and irreflexive portions formed on a rear face of the turn table, an LED (light emitting diode) for irradiating a light beam to the pattern on the rear face of the turn table from a position below the turn table, a photo-detector for sensing variation of reflected light from the pattern on the rear face of the turn table and for converting the variation of the reflected light to electric signals, and a signal processor for processing the electric signals outputted from the photo-detector. The frequency generator is widely used in the conventional optical disc apparatus for sensing the rotation of the optical disc, since the variation of the reflected light from the pattern on the rear face of the turn table corresponds to the rotation speed of the optical disc.
The conventional optical disc apparatus using the frequency generator needs the LED, the photo-detector, a printed circuit board for mounting the LED and the photo-detector, and interconnection wirings for connecting the printed circuit board and a main circuit board of the optical apparatus. Thus, it is difficult not only to lower costs but also to downsize of the optical disc apparatus.